The Basics on How Skin Cancer Develops
We’re told to wear sunscreen, keep to the shade, and to stay away from tanning beds all to avoid skin cancer. But do you know what really happens to your skin when its exposed to high UV rays or how skin cancer even forms? That question is pretty complicated and something scientists have been studying for decades. So, let’s break it down to just the basics.
To understand how skin cancer forms, we first have to understand what the sun does to our skin when its exposed and unprotected. Skin is the body’s largest organ and as the largest organ it has a large responsibility: protecting our bones, organs, muscles and tissues. There are two layers to our skin: the surface epidermis which is the very top layers, and the dermis, the deeper layers. In the dermis, keratinocytes, the cells that produce keratin, are made. As they are made, they are pushed upwards to the epidermis but have died by the time they reach the surface of your skin. While these cells are dead, they still perform the important role of protecting and water proofing all the layers underneath. And the dermis needs as much protection as it can get as it houses collagen, which helps provide resistance to damage, and elastin fibers which allows skin to stretch and recoil.
Ultraviolet (UV) radiation is a form of energy that comes from the sun. While sunlight is the main source of UV rays, you can also get them from other sources such as tanning bed lamps. There are three main types of UV rays: UVA, UVB, and UVC rays.
UVA rays age skin cells and damage their DNA, are the cause of some wrinkles, and are found in tanning beds.
UVB rays damage skin cells directly and cause most skin cancers as they are slightly stronger than UVA.
UVC rays aren’t strong enough to get through our atmosphere.
As UV radiation hits our skin it attacks the collagen and elastin fibers, leading to skin sagging, wrinkling, and roughness. But it doesn't just affect the look and feel of skin, it also increases the production of free oxygen radicals. These molecules attack skin cells, permanently damaging them and leading to premature aging. And while yes, UV radiation is required to get our fix of Vitamin D for the day, even just a few minutes outside in the sun will fill your quota.
In between the epidermis and dermis are cells called melanocytes. These cells when exposed to the sun produce a dark substance called melanin, which is what give you a tan or dark skin. Melanin is then absorbed by keratinocytes, which protects themselves from UV, but only to a certain extent, so a base tan or dark skin is not protection enough.
Now that we know how the sun damages skin, lets figure out why skin cancer begins to form in the first place. Just like UV rays, there are also three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma, and malignant melanoma.
The first two types of skin cancer, basal cell and squamous cell make up about 96% of skin cancer cases. They are tumors that form when keratinocytes have become damaged from the sun and therefore rapidly grow and divide. Basal cell carcinoma forms from keratinocytes in the dermis, while squamous cell forms in the epidermis. Melanoma on the other hand comes from a sun damaged melanocyte. While melanoma makes up only about 4% of skin cancer cases it is the most deadly because of its ability to grow fast and spread rapidly throughout the body.
Understanding skin cancer and how its caused is step one. The next step is to take preventative action. Skin cancer may be the most common cancer but its also the most preventable.